1. Technical Field
The present invention relates to a timepiece faceplate and to a timepiece.
2. Background Technology
A function required of faceplates for use in solar timepieces (timepieces provided with solar batteries) is the ability to transmit a quantity of light (optical transmission) sufficient for the solar batteries to generate sufficient electromotive force. For this reason, in the past, plastic members with high light transmission have been used as faceplates for solar timepieces. However, plastic typically lacks a high-quality feel, and is inferior in aesthetic appearance as compared with metal materials such as gold, silver, and the like. For this reason, there have been proposed faceplates obtained by causing a metal film comprising a metal material, and provided with an opening, to adhere to a substrate made of plastic, interposed by an adhesive (for example, Patent Citation 1).
However, with faceplates of this kind it has been difficult to achieve an exceptional optical transmission as well as an aesthetic appearance. More specifically, if a relatively high opening ratio of the metal film (the surface area of the opening as proportion of the entire metal film, when the metal film in viewed in a plane) is used in order to ensure transmission of light, the presence of the opening becomes conspicuous, and sufficiently exceptional aesthetic appearance is not obtained despite the use of metal material (metal film). On the other hand, if a low opening ratio of the metal film is used with the aim of improving the aesthetic appearance, transmission of light declines, and generation efficiency of the solar batteries markedly declines.
Also, particularly with methods such as the aforedescribed, the metal film is prone to wrinkling during adhesion of the metal film onto the substrate, and in order to prevent the occurrence of such wrinkles, it is necessary to carry out the adhesion procedure with care, and faceplate productivity is extremely low. Also, even in cases where the adhesion procedure is carried out with sufficient care, it has proven difficult to sufficiently prevent relatively small wrinkles or other flaws from appearing, and it has been exceedingly difficult to impart sufficiently exceptional aesthetic appearance to the faceplates obtained thereby, even in cases where the opening ratio of the metal film is low. Also, because a relatively high proportion of defective products occur, methods such as the aforedescribed are unfavorable from the standpoints of manufacturing yield and resource conservation. Problems such as the aforedescribed are particularly severe in cases where the metal film is relatively thin (for example, 10 μm or less). Also, in cases where the metal film is relatively thin (for example, 10 μm or less), the metal film is prone to tearing during the adhesion procedure, which is disadvantageous from the standpoints of faceplate productivity, manufacturing cost, and resource conservation; and portions of the torn metal film may get dispersed into the atmosphere as fine particulate, posing human health concerns.
Japanese Patent Application Publication No. 11-326549 (Patent Citation 1, see page 3, right column, line 35 to page 4, left column, line 11) is an example of the related art.